Optical processing applications in lightwave communications, optical computing and photonic switching are creating a need for high speed, high performance optical and photonic devices such as modulators and the like. While modulation-doped quantum well structures have been developed for such applications, the structures require have relatively high capacitance which limits the speed of operation of the device. Moreover, higher voltages are required to deplete the quantum wells which, if more than one is included in the structure, are depleted sequentially from top to bottom.